Chapter 9 and other stuff (Questions)

So I'm about to head to >!Prison Island in Chapter 9!< but decided I'd take a break to do some sidequesting. Questions

1. I have to do all the Refugee Camp sidequests before starting colony 6 or they'll expire right?

2. If I level down characters using Expert Mode, their arts and progress on upgrading the arts stays in tact right?

3. How long is Colony 6, I feel like it'll be super long so I wanna go ahead and start it now.

4. is there indication once you beat every sidequest in a given area?

Ty in advance